As far as price I didn't want to do your Fuso hunting a dis-service by quoting a number with virtually no information. 100,000 mi. isn't much The maintenance schedule in my owners book goes up to twice that. That's 5,000 mi. a year. However, if those miles were as a commercial snow plow in CO its a very different story. Is it a flatbed, dump truck, already a camper or cab and chassis?
I paid $22,500 for mine, new, in 1993 as a cab and chassis from Colorado Mack in Denver. That's factual but fairly useless information. You can buy a 1967 Ford Mustang for $1,500 but a one of a kind recently sold at an auction for $1,300,000.
I believe the 5 nut hubs are a standard 'Budd' 1 1/2" nut. Any place that works on trucks will have the right socket and square piece to undo the inner if you stick with duals. That might be important if you don't do your own work. I don't know why the switch was made to a 6 nut hub. Anybody know? I do know the nuts are larger because I was sent some by mistake. My intuition is that there isn't a strength problem with 5. The strength of 5 pieces of steel that size in single shear torqued to 350 lb-ft. could handle the shock load of one corner of a 6 ton truck.